Referring to the first invention and the second invention, an aromatic polycarbonate resin is excellent in properties such as a transparency, a heat resistance and a mechanical strength, and therefore it is widely used as a so-called engineering plastic in various industrial fields. In general, an aromatic polycarbonate resin produced by reacting 2,2-bis(4-hydroxyphenyl)propane (common name: bisphenol A) with a carbonic ester-forming compound such as phosgene and diphenyl carbonate is used as the above aromatic polycarbonate resin. Because of a good balance of a transparency and a mechanical strength with a moldability, an aromatic polycarbonate resin produced using this bisphenol A as a raw material is used as a raw material for electric and electronic equipments and optical equipments in many cases. In recent years, these equipments are increasingly demanded to be decreased in a size and a weight, and an aromatic polycarbonate resin which is further improved in characteristics such as a heat resistance and a mechanical strength without reducing basic characteristics endowed to this aromatic polycarbonate resin is requested to be developed in order to meet the above demand.
Then, in order to meet the above demand, it has been tried to obtain an aromatic polycarbonate resin which is improved further more in a heat resistance and a mechanical strength by using compounds having various structures as a divalent phenol which is a raw material for an aromatic polycarbonate resin. For example, an aromatic polycarbonate resin using a raw material of a bisphenol derivative of adamantane as divalent phenol is proposed in Soobsch. Akad. Nauk Gruz. SSR (1977), 88(3), p. 597 to 600. This aromatic polycarbonate resin in which an adamantane skeleton is introduced into a structural unit of an aromatic polycarbonate polymer chain has a high heat resistance but has the difficulties that it has a poor solubility in solvents because it is liable to be crystallized and it is inferior in a moldability and that the molded article is reduced in a transparency. Further, proposed are aromatic polycarbonate resins using a raw material of 1,1-bis(4-hydroxyphenyl)cyclohexane and 9,9′-bis(4-hydroxyphenyl)fluorene alone or in combination with bisphenol A as divalent phenol. However, these aromatic polycarbonate resins comprising a structural unit having a residue of divalent phenol has a higher heat resistance than that of an aromatic polycarbonate resin using bisphenol A as a raw material, but further higher heat resistance is required in the production steps of electric and electronic equipment parts. Thus, when used as a raw material for electric and electronic equipments and optical equipment parts, an aromatic polycarbonate resin which has further higher transparency, heat resistance and mechanical strength and which is excellent in a moldability is required to be developed.
An object of the first invention and the second invention is to provide an aromatic polycarbonate resin which is excellent in a transparency, a heat resistance and a mechanical strength and which has a good moldability and a production process for the same.
Referring to the third invention, various plastics are proposed as an optical part-molding material. Characteristics such as a heat resistance, an impact resistance, a mechanical strength and an optical property are required to the above optical part-molding material, and engineering plastics such as polymethyl methacrylate, polycarbonate using 2,2-bis(4-hydroxyphenyl)propane as a raw material, polyacrylate and polyethersulfone have so far been used as materials satisfying the above requirements.
On the other hand, some of a large number of these optical parts have a high transparency and require a very high heat resistance. For example, a liquid crystal display substrate of an active matrix mode in which a thin film transistor is arranged as a switching element for every picture element on a glass substrate in a matrix form and actuated is adopted in many cases. In a production step of the above liquid crystal display, an electrical insulating layer of silicon nitride has to be formed by a glow discharge deposition method when forming a thin film transistor on a substrate. Accordingly, since the substrate of the above liquid crystal display is glass, it is liable to be broken by impact exerted from the outside such as falling, and therefore it is desired to use a substrate of an engineering plastic having an excellent impact resistance. In the above engineering plastics, however, a heat resistance and an impact resistance are not satisfactory in, for example, polymethyl methacrylate, and a heat resistance in forming an electrical insulating layer is not necessarily satisfactory in polycarbonate and polyacrylate. Further, polyethersulfone has the difficulties that it has a high heat resistance but is colored amber and that optical anisotropy is liable to be brought about by slight molecular orientation.
Thus, an optical part-molding material which is excellent in a heat resistance and a mechanical strength in addition to an optical characteristic is requested to be developed as a molding material for optical parts.
An object of the third invention is to provide an optical part-molding material which is excellent in an optical characteristic and a mechanical strength and which has a particularly high heat resistance and an optical part prepared by molding the same.